Conventionally, an apparatus is known in which an automatic transmission is equipped in a drive train and in which a time point at which a load of a motor/generator which performs a revolution number control driven at a predetermined target revolution number is increased by a predetermined quantity is determined to be a time point at which a clutch engaged in a traveling range has started an engagement (refer to Patent Document 1).
In the conventional apparatus, during a mode switching from an HEV mode in which both driving forces of the engine and the rotor/generator are inputted to an input shaft of the automatic transmission to an EV mode in which the driving force of only the motor generator is inputted to the automatic transmission, an engine stop process and a separation process between the engine and the motor/generator (CL1 release) are carried out.
However, during the switching from the HEV mode to the EV mode at which these processes are carried out, the load of the motor/generator during a revolution number control in which a revolution number of the input shaft of the automatic transmission provides a target revolution number is varied regardless of an engagement state of the clutch engaged in a traveling range. Hence, when the above-described mode switching occurs before a determination of the engagement start of the clutch, the load variation of the motor/generator which occurs due to the mode switching is erroneously determined to be the engagement start of the clutch. This is a task of the present invention.